1. Field of the Invention
This invention relates to a universal joint of the kind which includes an outer joint member having a cavity at least partially within which is disposed an inner joint member, torque transmitting means interconnecting the outer and inner joint members for torque transmission whilst accommodating relative angular movement therebetween, the outer joint member being adapted to be connected to or being formed integrally with a shaft or other torque transmitting element and the inner joint member being formed with a bore adapted to receive a shaft, the shaft when thus received having torque transmitting relation with the inner joint member, e.g. by way of interengaging splines provided on the shaft and the inner joint member, and to a flexible sealing member for such a joint. Such a universal joint will hereinafter be referred to as a universal joint of the kind specified.
Universal joints of the kind specified are normally required to have a lubricant such as grease retained within the cavity of the outer joint member for lubricating the means which transmit torque between the inner and outer joint members. Such means may typically comprise balls engaging in complementary grooves in the inner and outer joint members, the balls being retained in a cage and being constrained, if the joint is a constant velocity ratio (homokinetic) joint, by suitable formation of parts of the joint to occupy a plane which bisects the angle between the rotational axes of the inner and outer joint members. For retaining such lubricant within the confines of the joint, and for excluding contaminants such as dust and grit therefrom, it is common to provide a flexible sealing member, normally termed a boot or gaiter, which covers the open end of the cavity and which will accommodate the angular movement between the inner and outer joint members. Such a boot is normally secured on the one hand to the periphery of the outer joint member, and on the other hand to either the shaft or the inner joint member.
Both these arrangements of sealing boot have disadvantages. If the boot is secured to the shaft, it is necessary to disconnect it from the shaft if for any reason the shaft should be required to be removed from the inner joint member. However, this arrangement has an advantage in that dirt is also excluded from the bore within the inner joint member and in which the shaft is received, which is of importance from the aspect of avoiding damage to the connection between the shaft and inner joint member, and from preventing dirt from reaching the torque transmitting parts of the joint by way of the bore. If the sealing boot is connected to the inner joint member, removal of the shaft does not entail dislocation of such connection, but the bore of the inner joint member is then left unprotected, and if it were required to prevent dirt from entering the bore this would necessitate the provision of a separate seal for this purpose.